import { PropertyReference } from "@/components";

# useCopilotAction

<br />
<img src="/images/use-copilot-action/useCopilotAction.gif" width="500" />

`useCopilotAction` is a React hook that you can use in your application to provide
custom actions that can be called by the AI. Essentially, it allows the Copilot to
execute these actions contextually during a chat, based on the user’s interactions
and needs.

Here's how it works:

Use `useCopilotAction` to set up actions that the Copilot can call. To provide
more context to the Copilot, you can provide it with a `description` (for example to explain
what the action does, under which conditions it can be called, etc.).

Then you define the parameters of the action, which can be simple, e.g. primitives like strings or numbers,
or complex, e.g. objects or arrays.

Finally, you provide a `handler` function that receives the parameters and returns a result.
CopilotKit takes care of automatically inferring the parameter types, so you get type safety
and autocompletion for free.

To render a custom UI for the action, you can provide a `render()` function. This function
lets you render a custom component or return a string to display.

## Usage

### Simple Usage

```tsx
useCopilotAction({
  name: "sayHello",
  description: "Say hello to someone.",
  parameters: [
    {
      name: "name",
      type: "string",
      description: "name of the person to say greet",
    },
  ],
  handler: async ({ name }) => {
    alert(`Hello, ${name}!`);
  },
});
```

## Generative UI

This hooks enables you to dynamically generate UI elements and render them in the copilot chat. For more information, check out the [Generative UI](/concepts/generative-ui) page.

## Parameters

<PropertyReference name="action" type="Action" required>
  The function made available to the Copilot. See [Action](#action).

    <PropertyReference name="name" type="string" required>
      The name of the action.
    </PropertyReference>

    <PropertyReference name="handler" type="(args) => Promise<any>" required>
      The handler of the action.
    </PropertyReference>

    <PropertyReference name="description" type="string">
      A description of the action. This is used to instruct the Copilot on how to
      use the action.
    </PropertyReference>

    <PropertyReference name="parameters" type="Parameter[]">
      The parameters of the action. See [Parameter](#parameter).

      <PropertyReference name="name" type="string" required>
        The name of the parameter.
      </PropertyReference>

      <PropertyReference
        name="type"
        type="'Primitive' | 'Primitive[]' | 'Record<string, any>' | 'Record<string, any>[]'"
        required
      >
        The type of the argument.
      </PropertyReference>

      <PropertyReference name="description" type="string">
        A description of the argument. This is used to instruct the Copilot on what
        this argument is used for.
      </PropertyReference>

      <PropertyReference name="required" type="boolean">
        Whether or not the argument is required. Defaults to true.
      </PropertyReference>

      <PropertyReference name="attributes">
      If the argument is of a complex type, i.e. `object` or `object[]`, this field
      lets you define the attributes of the object. For example:
      ```js
      {
        name: "addresses",
        description: "The addresses extracted from the text.",
        type: "object[]",
        attributes: [
          {
            name: "street",
            type: "string",
            description: "The street of the address.",
          },
          {
            name: "city",
            type: "string",
            description: "The city of the address.",
          },
          // ...
        ],
      }
      ````
      </PropertyReference>
    </PropertyReference>

    <PropertyReference name="render" type="string | (props: ActionRenderProps<T>) => string">
      Render lets you define a custom component or string to render instead of the
      default. You can either pass in a string or a function that takes the following props:

      <div className="ml-8">
        <PropertyReference name="status" type="'inProgress' | 'executing' | 'complete'">
          - `"inProgress"`: arguments are dynamically streamed to the function, allowing you to adjust your UI in real-time.
          - `"executing"`: The action handler is executing.
          - `"complete"`: The action handler has completed execution.
        </PropertyReference>

        <PropertyReference name="args" type="T">
          The arguments passed to the action in real time. When the status is `"inProgress"`, they are
          possibly incomplete.
        </PropertyReference>

        <PropertyReference name="result" type="any">
          The result returned by the action. It is only available when the status is `"complete"`.
        </PropertyReference>
      </div>
    </PropertyReference>

</PropertyReference>

<PropertyReference name="dependencies" type="any[]">
  An optional array of dependencies.
</PropertyReference>
